1. Field of the Invention
This invention relates in general to drop balls, plugs, or darts used to operate running well tool functions and, in particular, to a bypass sleeve with a dart landing shoulder to variably allow fluid flow past the drop member following tool operation.
2. Brief Description of Related Art
Darts, drop balls, or plugs are often used to actuate hydraulic devices within a wellhead or wellbore during well drilling and completion. Typically, a running tool is run to a predetermined location in a wellhead. A drop ball is then dropped into the running string supporting the running tool and pumped down to land at a shoulder within or axially below the running tool. Fluid pressure behind the drop ball is then increased until the fluid pressure reaches a level sufficient to actuate the hydraulic functionality of the running tool. The running tool may then be retrieved from the wellbore. This may be accomplished in a wet retrieval process. In a wet retrieval process, the running tool is pulled without first removing the column of fluid resting on the drop ball. This requires a tremendous expenditure of energy, and due to the significant weight of water being pulled, it is incredibly time consuming. In addition, the amount of water introduced into the deck level of the drilling rig can cause a significant safety problem to operators and workers located on the working deck.
Some devices may be pulled in a dry retrieval process. These devices include fluid ports that allow communication from the central passageway of the running tool to the wellbore. The fluid ports remain open during the operation of the running tool; thus, the fluid ports must be small enough to allow fluid pressure to build up behind the ball or dart despite the open fluid communication between the central passage of the running tool and the wellbore. When the device is retrieved, the fluid behind the dart will flow through the fluid ports into the wellbore. This eliminates the safety risk of the wet retrieval process by allowing the column of fluid blocked by the dart to drain past the dart during retrieval. However, this dry retrieval process is still incredibly time consuming as the process must be conducted slowly enough to allow the fluid to drain through the fluid ports without needlessly introducing fluid onto the platform deck.
One attempt to overcome this problem has been to include a burst disc in the dart to allow for faster draining of the drill string. However, because the burst disc must fit within the dart, it is, by necessity, smaller than the diameter of the fluid column above it. Therefore, while it does provide a faster drainage process than the previously described fluid ports, the burst disc still restricts flow and cannot maintain a large enough flowrate to drain as fast as the drill string can be pulled. Thus, there is a need for an apparatus to allow for a dry retrieval process that will decrease the time to retrieve the running tool, thereby decreasing the rig time needed and the cost associated with operation of the rig.